Optical square



Aug.- 2, 19.32. FT SCHNABL 1,869,512

OPTICAL SQUARE Filed Oct. 25. 1930 nVeno:

Patented lug. 2*, 1932 UNITED sTATEs PATENT oI-FlcE FRANZ SCHNABI, OF

JENA, GERMANY, ASSIq/NOB TO BAUSCH & LOMB OPTICAL C0., F

RocHEs'rEa,NEw YORK OPTICAL SQUARE Application led October All-glassreflecting bodies are generally used only with optical squareinstruments of small dimensions. Larger instruments of this kind consistas a rule of a support and reiecting glass plates. The inconveniencesinherent in this execution are stated in the United StatesLettersPatentl 995,235 which..

also explains how they can be overcome.

The present invention serves the same purpose and refers to a newsolution of the problem. This solution consists in ing glass plates ofsuch a form that those of its parts with which they are fixed to thesupport can readily adapt themselves to the deformations of the supportas are caused by changes in temperature, without forces that could causetensions of the reliecting part of the glass plates acting on the glassplates themselves.

The inventive idea can be realized by providing plates with heads thatare of the same piece as the glass plate and are each connected with thereflecting partof the same by a neck which is elastic owing to itscompara-l tively small diameter. Such heads are expediently provided onmore than one edge surface, when the support, which may con-- sist ofone or several parts, grips the glass plates at two edge surfaces whichare opposite to each other and when the glass plate, which may have anyconstruction,'is desired to be connected to several edge surfaces of thesupport. When the heads themselves are small, the desired elasticity canbe arrived at by using necks of a diameter wl ichy equals that of thesaid heads.

When the device forms a constituent part ofa measuring instrument, arangefinder for example, the connexion f oflthe .support to therangelinder may be similar to .that

' of the glass plates to this support. In this case it'is. advisable toprovide the support i with an v'attaching foot that is made of the vprovidat least one edge surface of the glass 23, 1930, Serial N0.490,801, and in Germany March 13, 1930.

same piece and isrconnected thereto by means of a thin connexion piece.

The invention naturally can be used quite as advantageously with opticalsquare instruments also when the reflecting parts are not of glass butof another suitable material, say quartz.

In ythe accom represents in square of 90 tion -with a rangeinder, planviewof same, and Figure 3 is a front elevation of a single reiectingpart of the optical square. I

The device represented in the drawing has a trapeziform support a ofwhich the lower surface, b, is connected with an attaching flange orfoot c by means of a thin connexion piece d. The flange c has holes efor insertingxing screws. On the two side edges of the support a, whichenclose an an le of glass plates f are fixed b'y means o rods g andthree screws h each. he lass plates f have silvered backs and take t eform of rectangular plates whereof one edge surface has two heads 1cformed integral therewith and connected thereto by thin necks i.

When the new optical square is in use and anying drawing Figure 1 rontelevat1on an optical deflexion for use 1n comunethe temperature changes,which would causeA Figure 2 is a top elasticity of the necks 'i allowsthese necks to yield so much that the rectangular relecting parts of theglass plates f remain without tension.l Also tensions which are causedby screwing the optical square to th liange o oftherangelinder are notimparted to the support; a by the connexion piece d.

and two reflecting members carried by said support, each of saidreflecting members beingl connected to said support by means of headswhich aneformed integral with the members and are connected thereto bymeans of relatively thin neck portions.

2. An optical square having in combination a support and a glassreiiecting member,

. FRANZ SCI-INABL;

